Tier 15
by IwasBornaRainicorn
Summary: After almost six years of friendship with Marceline, Jake still can't help but feel a bit suspicious of her and her motives towards his best buddy Finn. Especially when he overhears the strangest conversation the two teens are having in the vampires room. ONESHOT. warning hints of mature content.


Tier 15

In Jakes eyes, Finn was just a little kid, and no matter how old Finn got he would always be his naïve little brother that had a passion for adventure and meatloaf. It wasn't hard keeping this mindset when Finn was wearing diapers and doing funny little dances in the bathroom or when he was obsessed with beating Sleepy Sam in _Guardians of Sunshine_, but as time passed it started to become a bit of a challenge for Jake. Before he knew it his little brother was 17, and while the people of Ooo saw a young man, Jake still saw a little boy who still loved meatloaf, video games, and was horrible at talking to ladies. Maybe, just maybe, Jake went out of his way to avoid topics such as, "the birds and the bees" to make sure his little brother never changed. This would probably explain how traumatized Finn was after he saw his first _girl package_. Whenever it came to girl talk, Jake cut the line at smooching, because that's all his bro needed to know. The closest the two brothers ever came to _the talk_, was when Finn was fourteen and was crazy nuts for Flame princess. Jake very vaguely and briefly explained the different levels or tiers (as he worded it) in a relationship, hoping it'd be the first and last time they ran over the subject.

Jake still remembered how he snapped when Finn first asked about tier 15.

"_You stay away from tier fifteen! It's forbidden, don't ever go there man! I'm serious, don't do it! You've got no business there!"_

That scared Finn from asking anymore questions for the next three years, he probably thought tier 15 had something to do with scuba diving in an evil ocean. In hindsight Jake really should've known that his buddy would be curious about tier 15 every now and then, and if Finn couldn't get any answers from his bro, he'd find them from whoever was willing to teach him.

+.+.+

Jake didn't spend all day slaving away over a hot stove making one of his famous everything burritos, so Finn could be late for dinner. It was getting really late, and Jake couldn't help but worry his buns off. Last he heard of Finn was a few hours ago when he said he was heading off to deal with "a mysterious and possibly deadly emergency." Of course Jake wanted to tag along, but Finn got all flustered and insisted he'd be fine on his own.

Now Jake was sitting alone in the kitchen, with a cold everything burrito on the counter. He sighed and moaned loudly over and over, hoping Finn would sense his distress and come crashing through the walls, kind of like how he could sense when Finn was crying. But instead of Finn, BMO appeared on his skateboard.

"What is wrong Jake?" The little robot asked.

"What how'd you know something was wrong?"

"I can sense when your are being annoying."

"Yeah well whatever," Jake ignored BMOs last comment, "I'm just worried about Finn! It's dark out and he's not home yet!"

"Why are you worried, Finn is just jamming with Marceline?" BMO said, doing a tiny flip with his skateboard.

Jake's head snapped towards BMO, and he gave the tiny robot a look of disbelief, "What now, how'd you know that?"

"Finn told me."

"WHAT!" Jake lunged towards BMO and held him up close to his face, "WHAT DO YOU MEAN HE TOLD YOU! HE DIDN'T TELL ME NOTHIN'!"

"Calm down Jake, you shouldn't be worried now, Finn is safe with Marceline!"

But Jake was worried, really worried, twice as much as before even! Ever since he first met the vampire queen (and she tried to kill him) he was wary of her company. But as Finn got older, Marceline started hanging out a lot more with the duo, and slowly she grew on Jake, enough for him to go as far as risk his life just so she'd be safe (which he has done before, around four times, but seriously who's counting). Still there was something about that girl (probably the wicked demon faces) that scared the stuffing out of his donut. Finn always seemed to do ridiculous and dangerous junk when she was around, so in Jake's mind he had full right to be cautious around the vampire. He could just imagine what crazy junk they got into now, probably something awesome like chasing wolves or strangling evil pixies. Or maybe Jake was a little more jealous that he wasn't invited than he was worried.

"I'm gonna go get Finn, BMO protect my everything burrito with your life!" Jake called out behind him, as he headed out the door.

"Don't worry Jake! If anyone tries to eat your burrito I will kill them!" BMO replied trying to sound vicious, but ending up sounding all the more adorable.

+.+.+.

Jake headed out towards Marceline's cave, stretching his legs over large fields and hills to get there as fast as possible. He couldn't help but feel a little mad at Finn and Marcy for wanting to split a fun pie without him ( Jake loved fun pies, almost as much as tree trunks apple pies), what if Finn wanted to replace Jake with Marcy as his number one bro! Jake can't have that, just the thought of being left out forever made him quicken his pace. Once he was inside the cave he shrunk back down to his normal size, first he tried to open the doors but they were all locked, so instead he decided to sneak in through the doggy door (ninja style) Marcy had in the back for Schwabble. It took a little longer than expected, but after a good six minutes Jake squeezed his chubby butt in through the doggy door, he tumbled inside and when he knocked his head against one of Marceline's amps he face palmed and realized he could've just shrunk down and gotten through a lot quicker.

'_Something's fishy here... Something is definitely_ fishy' Jake thought while rubbing his chin and narrowing his eyes.

He walked around Marcy's living room feeling like that one famous detective from those Pre-Mushroom War books he found with Finn while they were out adventuring. What was his name? Cherlack Homes… Choorlick... Cha... Char... whatever it doesn't matter. Jake walked around, his hands folded behind his back, eyes darting to every corner of the room. Yes, there was definitely something fishy here!

There in a corner, next to one of the amps, was Marceline's ax bass. How could they possibly be _'jamming out'_ without a bass? The next thing Jake's genius skills of observation noticed was that the house was dead silent, no music was heard, this new discovery only reassured him that Finn was lying to BMO about _'jamming out'_. Jake wondered what he could possibly want to do with Marcy that he would have to not invite him and lie to BMO.

"Are you ready to do this?" Jake heard a muffled voice say. He almost forgot his last thought, and he crept towards the ladder.

"Hello? Finn buddy, is that you?" Jake quietly screamed, but he got no reply, there was a small wooden door shut tight over the hole that connected the bedroom to the rest of the house. Jake didn't recognize the door; it must've been newly installed.

Jake heard silent laughter coming from upstairs, and more pieces of a whispered conversation.

"I've always wanted to learn, but I didn't think you'd be willing to teach me Marcy!"

No doubt about it, that was his little brother in there talking to Marcy. Jake thought, he couldn't help himself, he wanted to hear their gossip, and soon enough he was climbing the stairs. He tried to open the latch on the door to sneak a peek but it wouldn't budge, so Jake had to settle for the mumbled conversation.

"Trust me Finn, your learning from the best and most experienced in all of Ooo. I'm no noob when it comes to stuff like this. So should we get started?" Marcy's voice asked.

Jake giggled, what could Marceline teach his little brother that he couldn't… probably something nerdy, like playing the accordion.

"Radical! But if we're really going though with this, it's gotta stay a secret. No one can know what happened here, especially Jake!"

She was definitely teaching Finn how to play the accordion, or something else to a similar degree of nerdiness. It's the only explanation for why his bro would want to be so secretive about it. Jake pressed his ear against the wooden surface, eager to hear his bro's sucky accordion skills.

"'Course Finn, you think I'm a huge blabber mouth? I'll keep things quiet until you're ready to go public. Also why would I ever want to spill the beans to your dog?" She chuckled

"Hey!" Finns voice snapped, "He's not my dog, he's my brother! And I hate keeping secrets from him."

Jake felt a tear sprout in his eyes, way to go Finn for defending Jake's honor. He couldn't be more proud.

"Don't be so hard on yourself hero, even a _virgin island_ like you has needs."

_What kind of needs would Finn have, other than kicking evil buns? _Jake thought, still eavesdropping.

Finn sighed, "Never mind… ok so what do we do first?"

"Easy just take your stuff out for me to see."

"Oh, alright."

"Wow Finn," A mischievous tone crept into Marceline's voice, "this sure is a pleasant surprise, that's some quality equipment you got going on, maybe a little small for my taste but it's not the size that matter. It's how you handle your equipment. And I'm sure you'll do great!"

"Stop it Marcy, you-your embarrassing me!"

"Oh come on just let me have a closer look."

"Oh glob Marci, can we just get this over with?"

"Well aren't you in a rush pupil? Ok then, let me just adjust myself in a more comfortable position… Ok Finn you see this hole, you've got to stick your stuff in it."

This...This does NOT sound like accordion playing. If Jake wasn't mistaken, this little chit-chat sounded kind of like _the talk _or even worse a demonstration of_ the talk_. No that's impossible Jake thought Finn doesn't even know how to ask princess bubblegum to go to the movies without embarrassing himself! Besides Finn would never go behind his back to do something like this!

"But-but Marceline! Its way too small, it'll never fit!"

"Make it fit Finn! You'd be surprise what you can fit inside this puny little hole."

"I'll try," Jake heard Finn grunting, struggling with something, "Ugh, I missed!"

"Keep at it hero, no need to get flustered. I mean not everyone can get it in on their first try."

All Jake could hear now were exasperated sounds from his little brother, and small gasps and groans. Jake needed to breath into a paper bag, he couldn't hear anymore of this without throwing up a little in his mouth.

"Marcy I can't do this!" Finn snapped, with a tone of annoyance.

"Just concentrate Finn." Marceline snapped back, matching his tone.

"Fine," Finn sighed, trying again, "Hey! Hey Marcy I got the tip in! I got the tip in!" Finn shrieked with joy, his voice hitting an almost piercing high octave that he hasn't reached since he was 14 and going through puberty.

Jake almost passed out and fell off the top of the ladder, but he kept his grip. He couldn't bear to leave, so he just stood stiff like an ice statue. He was so tempted to burst in there and stop things from getting any worse than they already were, but he was too scared, scared he might find two of his best friends in a very awkward situation that he would otherwise never want to see. Oh Glob, what if his eyes explode out of his sockets and go whizzing around in the air, and he's left blind forever! He'd never see another dawn, or another double rainbow!

Marceline's voice giggled softly, "Oh Finn! You're doing great so far; now just gently glide it in deeper and try to build up a nice rhythm to your movements! Here let me show you."

"Ok, I think I'm getting the hang of this!"

"Wow this is really good work for your first time! This is amazing Finn! You're a natural, see I told you the size of your equipment didn't matter!" Marceline sounded ecstatic.

"I still can't believe I'm really doing this with you!"

"Believe it babe! Please don't stop Finn," She squealed with delight, "Oh my glob you're doing perfect!"

"Look at who's getting all worked up," Finn chuckled, sounding a bit smug, "Marcy I'm gonna go faster, is that cool?"

"Do whatever you want Finn!"

All Jake could hear for the next few minutes, were sounds of heavy panting from his buddy, and words of encouragement and sounds of pleasure from Marceline. Jake's face contorted in displeasure, getting a nasty mental image that one should never get about their best buddy. There was no way things could get worse Jake thought, until he heard his little brother say something that made his jaw drop.

"Marcy, Marcy I'm almost finished! I'm so close!"

Not long after he heard them both scream, "YES!" in unison. And that was the last straw.

Jake's body grew twice in size and he hurdled himself against the small wooden door breaking it open, pieces of the door flew across the room. Jake landed on the floor, looking almost rabid.

"WHAT THE MATH IS GOING ON IN HERE!"

Marceline and Finn both looked towards Jake in surprise.

"Jake, what are you doing in here?"

"NO! THAT'S NOT IMPORTANT I WANT TO KNOW WHAT YOU TWO ARE-

Jake's anger immediately deflated like a balloon, when he looked up and saw Finn and Marceline, both fully clothed sitting up on Marceline's bed, Finn's hands hiding underneath the covers.

"Wait, what now, Finn what are you doing… What do you have in your hand?" Jake asked, feeling a bit suspicious. He didn't know if he should still be angry, considering they both seemed to have all their clothes on.

"Go ahead and tell him Finn." Marcy murmured, nudging Finn with her elbow.

"Tell me what?"

Finn nodded, and pulled out from under the covers his green pack. It looked brand new.

"Dude… your pack? I thought you ripped it open last week when we were rescuing Stanley the watermelon and his family from those evil elves?"

"Yeah I know! But I fixed it! All thanks to Marcy here," Finn turned and shared a smile with Marceline, at that moment he brushed his leg against the vampire, but Jake didn't seem to notice, his eyes filled with disbelief and locked on the backpack, "She taught me how to sew! Who would've known Marceline was such a great teacher!"

"Yeah, you pick up certain skills when you've been around 1000 years." She piped in, responding to Finns touch by slowly scooting closer to him.

Finn's face flushed red, "Yeah dude, sorry I didn't tell you why I was coming here before… I thought you'd make fun of me for learning how to sew, it's kinda girly."

"You still did great," Marcy patted his back in a way that seemed almost motherly, "Even if your needle was a bit too small, and you didn't have much thread, it still got the job done."

Jakes eyes glanced between Marcy and the small sewing needle stuffed inside a tiny tomato shaped needle holder, and the spool of light green thread lying on her covers. Suddenly it clicked inside Jakes head, and he felt relief flood through him. He started to laugh, while the two teens sat still and stared at him. Jake couldn't hold back his chortles; he held his stomach and laughed even harder.

"Oh thank Glob! You were just sewing! That's what all that noise was!"

Finn eyed Jake with confusion, "Yeah dude, what'd you think we were doing?"

"Oh a nothing!" Jake quickly shut up, not wanting to seem suspicious; he wondered what Marcy would do to him if she knew he was eavesdropping on them the whole time.

"You sure Jake?" Marceline asked, slinging one of her arms over Finns waist and nuzzling her head against his shoulders, her voice came out as mischievous and sly as a fox "You didn't think me and Finn were doing anything wrong did you?"

Jake blushed and quickly tried to come up with an excuse to leave, "No! Uh, Finn we've got to get going, I've got dinner waiting!"

"Oh sure dude, let me just finish packing up my stuff." Finn said, jumping out of bed and stretching his sore limbs.

"Hey Finn," Marceline called with a pout on her lips, Finn turned to her, " I thought we had a deal, I help you fix up your pack and you help me record my newest track for my concept album."

"Aw poop, I totally forgot... Sorry bud I'm gonna have to stay awhile longer! A hero is always true to his word!"

"But Finn!" Jake complained, he came out all this way and was almost traumatized for nothing! "My everything burrito is waiting for us!"

Finn crouched down to Jakes level, a pleading look in his eyes, "I'm sorry bro, I promise I'll make it up to you OK! I can heat up burrito left over's when I get home ok, but right now Marceline needs me."

"Oh fine. I guess I'll see you at the tree fort," Jake said disappointed, he turned to wave at Marceline, "Bye Marcy."

She smiled innocently and waved back, "Bye Jake."

+.+.+.

Jake walked back home feeling content, knowing that his little brother was still as naive and innocent as he was when he was 12 years old and rolling around in mud puddles… actually Jake saw Finn do the same thing last week too. Jake was glad, his little brother rarely changed. Still Jake knew he couldn't keep up the illusion forever, he doubts Finn will keep rolling around in mud puddles when he's in his 30's.

Jake decided that night on his walk, that when Finn got home, and after he finished his reheated everything burrito Jake would finally have _the talk_ with Finn. No matter how embarrassing and uncomfortable things got, it had to be done. And maybe he'd delve a little deeper into what Tier 15 actually was, so Finn wouldn't think it was an evil ocean all his life.

He'd rather Finn hear it first from his older brother than from an unreliable source.

+.+.+.

Finn was standing by Marceline's bedroom window, watching his buddy leave the cave. The farther away Jake got, the harder it got to see him, and eventually he turned into a tiny yellow spot in the black night.

"Hey Finn is he gone yet?" Marcy called from the bed.

Once the yellow dot completely vanished, a satisfied Finn glanced back at Marcy and called:

"The coast is clear!"

Marceline quickly tossed Finns green pack and all the sewing junk off the bed and tore off her gray shirt.

"You ready for round two hero?" She asked, her voice a low seductive purr, slipping out of her skinny jeans and beckoning for him to come back to the bed.

"YOU KNOW IT!" Finn yelled, pulling down his blue shorts and bounding back towards the bed.

Marceline clung to him like a koala bear and buried him underneath her covers, pressing her bare chest against his shirt. She kissed his soft, quivering and inexperienced lips until they bruised. Between kisses and sweat coated skin, Finn smiled up at the girl that he willingly allowed to steal his purity.

* * *

**i know I haven't written anything for fanfiction in a LONG time. I really missed it, but i've either been ridiculously busy or ridiculously lazy. I'm sorry for my lame butt excuses to those who are fans of "into the dark" and were hoping for an update. Honestly, that story might stay on hiatus for awhile, i mean i've written half of the next chapter for that story already but it just feels like my writing has turned into crap. I feel like i needed some time on a different subject, so i decided to start righting for my next favorite fandom ADVENTURE TIME and MARCELINExFINN is one of my favorite pairings. I hope you guys enjoy this awkward little one shot... it took about two days to write, and it was partly inspired by "listening in" by moonlight escape. Gotta give that gal some credit. Thanks for writing that fanfic, i totally loved it, and if it wasn't for you i probably would've never written this. **

**what else to say... i don't own adventure time... if i ever get the whim to write more fanfic it'll probably be more one shots for adventure time. i don't think im ready to commit to one long chapter story. im not responsible enough. **

**thanks for bearing through with me in this LONG story and this LONG authors note. I hope you like this, please review. **

**thank you may you live a long and happy life. **


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